Tire testing (tire uniformity testing) has been hitherto carried out. In the tire testing, tire uniformity or the like is measured on a tire finished as a product to thereby determine the quality of the tire. For example, when tire uniformity is measured on a tire for a passenger car, the tire testing is generally performed in the following procedure using a tire testing device as shown in Patent Literature 1.
That is, the tire testing device in Patent Literature 1 has an air pressure circuit. In the air pressure circuit, compressed air which has been supplied from a factory air source (air supply source) and whose pressure has been adjusted is supplied to a tire seated on a rim. The tire is inflated by the air pressure circuit, and tire uniformity testing is then performed thereon. The air pressure circuit has two systems of pipe arrangements branching halfway. One is a pipe arrangement of a bead seat system for inflating the tire in a short time to mount the time on the rim, and the other is a pipe arrangement of a test system to be used for testing the tire. The pipe arrangement of the bead seat system and the pipe arrangement of the test system are changed over using a changeover valve. Thus, the air pressure circuit can inflate the tire through paths of the pipe arrangements of the two systems.
When the tire testing is performed by the tire testing device, the tire having flowed from the upstream side of a testing line is first held by the rim which is divided into upper and lower parts. Next, the tire is inflated in a short time using the pipe arrangement of the bead seat system. On this occasion, the air pressure of compressed air supplied to the tire using the pipe arrangement of the bead seat system is generally set at a higher pressure (for example, about 400 kPa) than a test pressure (test air pressure) for the tire testing. The tire is kept at the test pressure for about one second including a pressure increase time.
Next, in the tire testing device, the flow path of the compressed air is changed over from the pipe arrangement of the bead seat system to the pipe arrangement of the test system using the changeover valve. A pressure adjustment valve is provided in the middle of the pipe arrangement of the test system so that the pressure of the high-pressure compressed air can be reduced to the test pressure (for example, about 200 kPa). Thus, when the compressed air is supplied through the pipe arrangement of the test system, the air pressure in the tire can be adjusted to the test pressure. Then, the tire kept at the test pressure is rotated, and pressed against a drum. Repulsion force generated in the tire is measured using a load measuring unit provided in the drum. Thus, the uniformity of the tire is measured.
A servo-type pressure regulator may be used as the aforementioned pressure adjustment valve as described in Patent Literature 2.